The prior art has in principle disclosed reinforced thermoplastic molding compositions based on styrene copolymers.
The use of fillers and reinforcing substances for modification of properties is attractive in amorphous materials. However, there are so far only a few examples of attempts to add fillers to styrene copolymers.
DE 41 14 248 A1 discloses thermoplastic molding compositions composed of from 40 to 95% by weight of a copolymer A composed of from 90 to 50% by weight of styrene, of α-methylstyrene, of a ring-substituted styrene derivative, or of mixtures of these monomers, and from 10 to 50% by weight of acrylonitrile, up to 50% by weight of a graft copolymer as component B, from 1 to 50% by weight of a reinforcing agent based on an inorganic glass as component C, and also from 0.1 to 50% by weight of a terpolymer D based on styrene-methyl methacrylate-maleic anhydride, and, if appropriate, other comonomers in each case using from 1 to 15% by weight of styrene and maleic anhydride and using a styrene-maleic anhydride ratio of from 5:1 to 1:5.
EP 0 303 919 A2 likewise discloses reinforced thermoplastic molding compositions, composed of three components A, B, and C. This molding composition comprises, as component A, from 40 to 94% by weight of a copolymer, composed of from 90 to 50% by weight of styrene, of α-methylstyrene, of a ring-alkyl-substituted styrene derivative, or of mixtures of these monomers, and from 10 to 50% by weight of (meth)acrylonitrile and/or methyl(meth)acrylate. The molding composition comprises, as component B, from 20 to 0.5% by weight of a terpolymer, composed of from 90 to 50% by weight of at least one monomer from the group consisting of styrene, of α-methylstyrene, of the ring-alkyl-substituted styrenes, or of mixtures of these monomers, from 5 to 40% by weight of (meth)acrylonitrile and/or methyl(meth)acrylate, and from 2 to 30% by weight of another monomer, and it is essential here that the terpolymer B comprise tert-butyl(meth)acrylate as other monomer. The molding compositions also comprise from 5 to 50% by weight of a reinforcing agent as component C.
DT 1 949 487 discloses thermoplastic molding compositions based on copolymers composed of maleic anhydride, styrene, and acrylonitrile, and copolymers composed of styrene or α-methylstyrene, and acrylonitrile or methacrylonitrile. The molding compositions according to DT 1 949 487 have high heat resistance but are too brittle for many applications.
DE 35 15 867 A1 discloses reinforced thermoplastic molding compositions, composed of component A from 5 to 95% by weight of at least one copolymer, composed of from 90 to 50% by weight of styrene, of α-methylstyrene, of a ring-alkyl-substituted styrene derivative, or of mixtures of these monomers, and of from 10 to 50% by weight of (meth)acrylonitrile, and also component B from 95 to 5% by weight of at least one terpolymer comprising styrene as monomer unit, and, as component C, from 5 to 50% by weight of a reinforcing agent. According to DE 35 15 867 A1, the molding composition comprises, as terpolymer B, a terpolymer which is composed of from 90 to 59% by weight of a monomer from the group consisting of styrene, of α-methylstyrene, of the ring-alkylated styrenes, or of mixtures of these monomers, from 8 to 48% by weight of (meth)acrylonitrile, and from 2 to 30% by weight of a monomer from the group consisting of acrylic acid, of methacrylic acid, of maleic anhydride, or of mixtures of these monomers. The molding composition comprises, as reinforcing agent C, glass fibers known per se.
All of the terpolymers B used according to the examples of DE 35 15 867 A1 comprise a proportion of maleic anhydride which is 5% by weight or higher.
The heat resistance of the molding compositions according to DE 35 15 867 A1 in particular is too low for most applications.